Automatic Dependent Surveillance Broadcast (ADS-B) is the global standard for modern air traffic monitoring. Aircraft broadcast unencrypted radio signals on 1090 MHz containing their Mode S 24-bit hex address, barometric altitude, ground speed, and position.

Through a worldwide network of open receiver stations, millions of position reports are captured every hour. This article explains how raw telemetry turns into structured airline fleet intelligence.

From Radio Messages to Discrete Flights

Raw ADS-B messages arrive asynchronously at receiver stations. A single flight generates thousands of position packets between pushback and gate arrival.

To convert this continuous stream into structured operational data:

  1. Airframe Isolation: Position points are grouped by the unique 24-bit Mode S transponder hex identifier.
  2. Phase of Flight State Machine: Altitude and ground speed thresholds determine whether an airframe is in ground transit, takeoff roll, cruise flight, approach, or landing roll.
  3. Airport Snapping: When a transition from airborne to ground state occurs, coordinates are snapped against the OurAirports database using the Haversine formula to identify arrival and departure fields within 3.0 km of a runway.

Handling Incomplete Signals and Edge Cases

Real-world radio coverage is not uniform across the globe. Flights crossing oceanic corridors, polar routes, or regions with sparse receiver density require specialized processing rules:

  • Traces Starting Airborne: Flights already in cruise at 00:00 UTC are tracked with an airborne start flag to avoid false cycle counts.
  • Traces Ending Airborne: Long-haul flights continuing past 23:59 UTC are completed in the subsequent daily ingestion window.
  • Low-Coverage Region Labeling: Where receiver density is low, confidence indicators are adjusted downwards to ensure inactive counts reflect observation limits rather than true grounding.

Every number on this platform is derived through deterministic state rules, providing an open, reproducible picture of commercial aviation activity.